lol i have always backed up my stuff, i've been fortunate to have never suffered a loss. a good backup schedule and a good host has seen to that.
Backing up your web site is very important. Don't forget to BACK UP! Do yourself a favor and just do it.
And keep your backup somewhere else! At a friends house, parents, school locker etc. Otherwise if your house is burgled/floods/burns you'll be fuked. Yeah, an external drive (stored somewhere else) gives you a warm glow of invincibility. I know 2 guys that wirelessly backup their drives to each others computers (they're neighbours) everyday. You can never have too many backups.